The increasing vulnerabilities is another striking impact of our CO2 emissions. Anyone who likes moules frites would be well advised to push for action to reduce our reliance on fossil fuels to keep them on the menu.

Cross section of a mussel shell showing thickness. The holes show were samples were drilled to analyze its composition.

Shells from the Pacific Northwest are nearly a third thinner now than specimens collected in the 1970s

As humans burn fossils fuels, the oceans absorb a large portion of the additional carbon released into the atmosphere. This in turn causes pH levels of ocean water to drop, making it more acidic. Mussels, oysters, and certain species of algae have difficulty producing their calcium carbonate shells and skeletons in such an environment, and can provide an early indicator of how increasing ocean acidification affects marine life.

A new study by University of Chicago biologists shows how those effects are coming to pass. They compared shells of California mussels collected from the Pacific Ocean off the coast of Washington in the 1970s to modern specimens, and saw that the older shells are on…